1. Field of the Invention
The present invention concerns a device adapted to be associated with a group of input or output channels of a programmable control system, especially a programmable automatic controller, in particular to detect if the channels in question are subject to an electrical fault referred to as a line fault such as an open circuit and/or an overcurrent.
2. Description of the Prior Art
Existing input devices for programmable automatic controllers comprise input channels connected to sensors and a circuit for serial routing of data relating to a group of input channels. The serial routing circuit is connected to an input and/or output control unit in turn connected to a central processor unit and it is adapted to transmit to the control unit words made up of data bits relating to the channels consecutively scanned.
It would be beneficial for an input device of this kind, described in the U.S. Pat. No. 5,062,072 to be able to detect line faults representing an incident such as inadvertant opening of an input or output circuit or a short circuit on an output channel.
A particular object of the invention is to enable detection of line faults affecting input or output channels of an automatic control system such as a programmable automatic controller and to advise the input and/or output control unit of the system of such faults by means of comparator cells enabling adaptation to diverse input or output situations.